1. Field of the Invention
The present invention relates to a wireless communication system, a wireless communication device, a wireless communication method and a computer-readable medium therefore for packet transmission. More specifically, the present invention relates to a wireless communication system, a wireless communication device, a wireless communication method and a computer-readable medium therefore for defining packet transmission rules between nodes.
2. Descriptions of the Related Art
Low speed wireless communication devices are highly noticed recently in the fields of household appliances, toys, industries, security services, and medical care. For the characteristics of low cost, low power consumption, and easily disposed, it is especially proper to be applied in low maintenance and broad service area. Among various low speed wireless communication protocols, the most representative standard is IEEE 802.15.4/ZigBee.
Whereas most wireless communication devices are restricted by radio wave strength, the coverage is limited. When a large service area is desired, access points are usually needed to dispose a union of radio wave coverage. As shown in FIG. 1, when information is transmitted from a node 11 to a node 13 and radio wave coverage 11A of the node 11 does not cover the node 13, thus, the information is transmitted to an access point 12 first, and then, the access point 12 passes the information to the node 13 by way of the radio wave coverage 12A of the access point 12. In this kind of network, choosing different routing and various controls thereof should be achieved by broadcasting data packets.
Owing to the broadcast in a large-scale wireless network should be made by relay of a plurality of nodes, the nodes, used for transmitting broadcast packets, must assure that all of the connecting nodes could receive packets accurately to ensure the broadcasting packet could be transmitted to every node in the whole service area. However, there is no “acknowledging packet” in the manner of broadcasting. Accordingly, the transmitting node is unable to comprehend whether the packet is received by the receiving node accurately. Under the current skills, multiple unicasting or monitoring whether the connecting nodes relay the packet are used to judge if a packet requires being re-transmitted or not.
The prior art of the above-mentioned will result in problems shown as the following. The nodes would not receive packets accurately when they are in a doze mode. Consequently, the hidden terminal problem would cause collisions and lead to misjudgments. Thereafter, a large number of packet re-transmissions, excessively long delayed time, and waste of operations on a single node are generated.
According to the above descriptions, a wireless communication system and method that could deal with packets and save bandwidth are badly needed in the industrial field.